The grainy texture on the images looks great and makes this really feel like a pre-Flash cartoon of the 90s or earlier. You also really nailed the art style, and it really makes the animation pleasant to the eye.
Humor-wise I didn't find this especially entertaining, but it's only 2 minutes so the unfunny-ness isn't that painful to sit through, especially when the aesthetic makes up for it a lot.
There are two main hiccups that I think drags this down considerably. First, some of the animation is just way too simple. Some of the really simple stuff (like the camera pan in the beginning) have a low framerate and look jerky. The two frame loop of the rat digging through boxes looks really crude, and it wouldn't have taken THAT many more frames to create a loop (even a low framerate one) that looked less sloppy. The screen shake at the very end is another example of this - just a few more frames to slow this down would make it look more like something that might actually air on Cartoon Network.
The second issue is the timing. Not just comedic timing, but the timing of the shots as well. It's a short animation (under 2 minutes) yet panning and fading transitions are all we see for the first 30 seconds of it. Some of the relatively short shots should be even shorter, like the rat tearing apart the box, or the first shot of him reaching into it (you play the same loop later and that time it's shown for the right amount of time.) Similarly, both shots of the rat holding the snow globe are just a little too long, as well as the still shot of the mess the rat made. All of these things might seem like nitpicks, but if you imagine how awkward it might be to talk to someone that randomly inserted... half second pauses while speaking... to you, it makes sense how not only these small differences of a fraction of a second can create a disruptive experience, but how a bunch of them back to back make the final product look unpolished.